A high speed downlink packet access (HSDPA) technology is introduced to Release 5 (R5) of the 3rd Generation Partnership Project (3GPP), and by using a series of key technologies such as adaptive modulation and coding, hybrid automatic retransmission, higher-order modulation, base station 2 ms fast scheduling, and the like, downlink high-speed data transmission is achieved.
In an HSDPA system, a user terminal measures quality of a received radio channel, where each channel quality level corresponds to one channel quality indicator (CQI) value, and returns a CQI value to a base station. After receiving the CQI, the base station, with reference to usable power resources and code resources and a data volume in a transmission cache, transmits data blocks in a proper size by adopting an appropriate transmit power, the appropriate number of code channels and an appropriate modulation manner. This is the adaptive modulation and coding technology in the HSDPA system.
The inventor of the present invention finds that accuracy of CQI feedback has a severe impact on a data transmission rate in HSDPA. Accuracy of CQI measurement is related to an implementation algorithm of a user terminal, which is uncontrollable by a network side.